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authorGabriel L. Somlo <gsomlo@gmail.com>2014-02-27 23:06:17 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2014-03-13 11:58:21 +0100
commit100943c54e0947a07d2c0185368fc2fd848f7f28 (patch)
treea69aea55ffa31a8d365974f8c9217a339cdfb27f /virt
parentfacb0139698923dc7b7d15cafbb319219969f4fd (diff)
downloadkernel-100943c54e0947a07d2c0185368fc2fd848f7f28.tar.gz
kvm: x86: ignore ioapic polarity
Both QEMU and KVM have already accumulated a significant number of optimizations based on the hard-coded assumption that ioapic polarity will always use the ActiveHigh convention, where the logical and physical states of level-triggered irq lines always match (i.e., active(asserted) == high == 1, inactive == low == 0). QEMU guests are expected to follow directions given via ACPI and configure the ioapic with polarity 0 (ActiveHigh). However, even when misbehaving guests (e.g. OS X <= 10.9) set the ioapic polarity to 1 (ActiveLow), QEMU will still use the ActiveHigh signaling convention when interfacing with KVM. This patch modifies KVM to completely ignore ioapic polarity as set by the guest OS, enabling misbehaving guests to work alongside those which comply with the ActiveHigh polarity specified by QEMU's ACPI tables. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Gabriel L. Somlo <somlo@cmu.edu> [Move documentation to KVM_IRQ_LINE, add ia64. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/ioapic.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index ce9ed99ad7dc..1539d3757a04 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -328,7 +328,6 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id,
irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq],
irq_source_id, level);
entry = ioapic->redirtbl[irq];
- irq_level ^= entry.fields.polarity;
if (!irq_level) {
ioapic->irr &= ~mask;
ret = 1;